A wide variety of cameras, film cassettes, bulk film containers and the like store a long, relatively narrow filmstrip as a cylindrical film roll. (The terms "film" and "filmstrip" are used herein to refer to the same physical article. "Film" is used as the more general term. "Filmstrip" is used where it is desired to emphasize that the film, when unrolled, has the form of a long, narrow rectangle.) The roll of film is, in many cases, wound around a central spool or core. In other cases, the core is deleted in an effort to reduce expense, complexity, and weight and the film is in the form of a coreless roll or "roll".
Rolls can be formed by simply transporting a filmstrip into a cylindrical or similarly shaped storage container or camera film chamber. For example, a variety of cameras are known in which a film roll is formed by prewinding unexposed film from a cartridge or spool. U.S. Pat. No. 1,921,559 and U.S. Pat. No. 1,921,560 teach thrust cartridge cameras which prewind to an empty roll chamber having generally concave walls. This approach has the advantage that handling of the roll is minimized, since the roll is formed in situ. This approach has the problem that it tends to require the use of a filmstrip having specific curling properties and becomes problematic when the length of the filmstrip is increased.
A solution to this problem is using an appliance to help shape the roll as it is formed and then removing the appliance. A limitation of such appliances is that the appliance itself requires a certain amount of free space in a specific shape and position or range of positions. This constrains the design of the camera body or film container. A variety of different loading methods and appliances have been used in an attempt to optimize characteristics within these constraints.
Roll forming methods using appliances can be roughly categorized into methods using appliances acting external to the roll, methods using appliances acting internal to the roll, and methods using a combination of internal and external appliances.
External-acting appliances have the advantage that the film does not need to be attached to the appliance during film rolling. The following references teach methods and apparatus in which an external-acting appliance is used.
U.S. Pat. No. 3,057,573 teaches a camera having roll chamber defined by three opposed rollers, which resiliently move apart as the roll diameter is increased. One of the rollers is fixed. The other two are mounted in a movable carrier. U.S. Pat. No. 4,440,483 teaches a camera having a roll chamber defined by curved walls and an arcuate lever. The lever is spring biased to bear against a film roll within the chamber. U.S. Pat. No. 3,288,389 teaches the formation of a roll in a film cartridge within a resilient band of rubber of the like. The band may be lined by foil or other flexible material. U.S. Pat. No. 2,484,248 teaches a similar cartridge having a metal spring. In each of these approaches, the film roll is subject to the compressive force of the springs or resilient band during film use. This compressive force is undesirable, since it puts the rolled filmstrip at risk of scratching. U.S. Pat. No. 5,016,833 teaches a document roll-up system in which media sheets are rolled in a space defined by a pair of external guides and a "C ring".
These various methods either resiliently compress the film roll as it is wound, presenting a risk of scuffing; or rely on cumbersome devices that require access from multiple directions and are thus impractical to use to wind film within an enclosure smaller than the devices themselves; or both.
It would thus be desirable to provide a relatively simple film loader and film loading method which require access to the interior of the chamber from only one direction.